Abstract
This paper presents numerical results of rapid depressurization of a channel containing saturated hot water under high pressure discharged into an air region at atmospheric conditions. Such processes are typical for accident scenarios in thermal-hydraulic systems, power installations, and high-pressure pipelines and are characterized by strong pressure gradients and complex wave structures. The two-phase water–air flow is described using the Euler equations in conservative form within the framework of the homogeneous equilibrium model, employing the stiffened gas equation of state for water and the ideal gas model for air. Numerical simulations are performed using a first-order explicit finite-volume method with the Rusanov scheme, ensuring stability in the presence of strong pressure and density gradients. The time step is determined using the CFL stability condition. The study analyzes liquid expansion, propagation of rarefaction waves, phase mixing, and temperature field evolution during rapid pressure release. The obtained results demonstrate consistent evolution of pressure, velocity, and phase distribution fields, con-firming the physical validity of the proposed model. The proposed approach can be applied to the analysis of accident processes in high-pressure engineering systems, modeling of mass and energy transfer, and investigation of fluid–gas interaction mechanisms during rapid depressurization processes.